This invention relates to thermosettable bisimide compositions. In one aspect, the invention relates to the preparation of cured bismaleimide resins having enhanced fracture toughness.
Advanced composites are high-performance materials made up of a fiber-reinforced thermoplastic or thermosettable material. The thermosettable materials useful in advanced composites must meet a demanding set of property requirements. For example, such materials optimally have good high-temperature properties such as high (above 200.degree. C.) cured glass transition temperature and relatively low (less than 4%) water absorbance at elevated temperature. Such material must also exhibit high mechanical strength, as measured by fracture toughness and compression after impact. For ease of processing in preparing prepregs for composite parts, the uncured material will ideally have a low (below 120.degree. C.) melting temperature.
Bismaleimide resins are thermosettable resins with much promise for use in advanced composites. Disadvantages of bismaleimides, however, include brittleness and high melting points, the latter of which requires most bismaleimides to be used with solvents for acceptable processability.
It is therefore an object of the invention to provide bisimide resin compositions having enhanced physical properties for composites applications.